Pabian, R. K, 1977. Sarpy County, Gretna State Fish Hatchery Area Field Guide (FG-3) 7 pp., size 8.5" x 11". Description: Recent emphasis in the Earth sciences has created a demand from teachers and students for geologic information in the area in which they live. In addition, rock collecting has grown to one of the nation's most popular hobbies. Many students and hobbyists want to identify the rock layers and geologic features they see in the field. This field guide series has been prepared to help the nonprofessional familiarize him/herself with the stratigraphy and some of the geologic phenomena of Nebraska.